1. Field of the Invention
The present invention relates to a laser induced thermal imaging apparatus and, more particularly, to a laser induced thermal imaging apparatus capable of simultaneously performing lamination and laser irradiation, and a laser induced thermal imaging method using the apparatus.
2. Description of the Related Art
In general, a laser induced thermal imaging (LITI) method requires at least a laser, an acceptor substrate, and a donor film. The donor film includes a base film, a light-heat conversion layer and a transfer layer. In an LITI process, the transfer layer is disposed opposite to the acceptor substrate to laminate the donor film on an entire surface of the acceptor substrate, and then to irradiate a laser beam on the base film. The beam irradiated on the base film is absorbed into the light-heat conversion layer to be converted into heat energy, and the transfer layer is transferred on the acceptor substrate by the heat energy. As a result, a transfer layer pattern is formed on the acceptor substrate. This is disclosed in U.S. Pat. Nos. 5,998,085, 6,214,520 and 6,114,088.
However, when the donor film is laminated on the entire surface of the acceptor substrate as described above, bubbles may locally remain between the acceptor substrate and the donor film. These bubbles may cause transfer failures.
In order to solve the problem, U.S. Pat. No. 6,226,020 discloses a method and apparatus for producing a print by means of laser induced thermal transfer. In accordance with '020 patent, a pattern is formed on the substrate by contacting a transfer tape having a width smaller than that of the substrate on the substrate provided on a substrate cylinder, and irradiating a laser beam on the transfer tape. At this time, contacting the transfer tape on the substrate is performed using a contact roll adjacent to the substrate. Additionally, a nozzle is disposed in a direction inclined to the laser beam, and a gas is ejected on the transfer tape using the nozzle to improve contact force between the transfer tape and the substrate.
Specifically, the contact roll functions to allow the transfer tape to surround the substrate cylinder with a predetermined wrap angle, and the wrap angle may form contact force and friction force between the transfer tape and the substrate on the substrate cylinder. However, when the transfer layer of the transfer tape is an organic layer, the friction force generated as described above is sufficient to damage the organic layer.
In addition, the nozzle is disposed in the direction inclined to the laser beam, since a distance between the nozzle and the substrate is too far, it may be difficult to obtain sufficient contact force between the transfer tape and the substrate using only the nozzle. In this case, in order to obtain the sufficient contact force, the nozzle should eject a plenty of high-pressure gas on the transfer tape. In particular, differently from '020 patent, when the substrate is not wound on the cylinder but located on a plane surface and the transfer tape and the substrate should be closely adhered to each other using only the gas pressure ejected from the nozzle without the contact roll, it may be more difficult to sufficiently obtain uniform contact force all over a predetermined region due to the far distance.